Industrial gases such as those obtained from the fractionation of air, can be delivered and utilized with the use of portable compressed gas cylinders. For instance, hospitals routinely use portable gas cylinders containing breathable compressed gases for patients during the course of their stay. The gas cylinder is normally connected to a pressure regulator to reduce the pressure of the gas and a flow meter to control the flow of the gas to the patient.
Gas cylinder dispensing valves have been introduced that incorporate a pressure regulator and a flow control valve within a valve body. The valve body is designed to be connected to a gas cylinder containing the breathable gas to be dispensed for patient uses. The primary problem with the use of such dispensing valves is the tendency of the valve to leak between its filling and usage. This is mostly due to temperature shrinkage of different materials utilized within the valves.
In order to overcome this problem, U.S. Pat. No. 5,996,625 provides a dispensing valve that incorporates an isolation valve that can be set to cut off the flow of the gas within the valve. The device illustrated in this patent incorporates an isolation valve set transversely to the axis of rotation of control knobs that are located at the top of the body of the valve. The isolation valve is not biased and is toggled between open and closed positions by force applied to opposite ends of the valve that protrude from the valve body. The isolation valve is activated by a control knob having a tubular member covering the valve and provided with an internal cam-like surface to contact opposite ends of the valve to toggle the isolation valve. A top portion of the control knob is recessed to contain a separate control knob to adjust a flow control valve and therefore the gas flow rate of the gas to be dispensed. Hence, setting the valve in open and closed positions and adjusting the flow rate requires two separate motions by manipulation of the two control knobs.
As will be discussed, the present invention provides a gas cylinder dispensing valve having both a flow control valve and an isolation valve that are both manipulated by a single control knob. This simplifies the setting of the valve. Moreover, the present invention allows the dispensing valve to be constructed in a manner that is straight forward and thus, far less complicated than prior art designs.